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我在String类上使用扩展来获取在多行标签中显示我的字符串所需的高度。Swift:boundingRectWithSize为多行标签返回错误的高度
extension String {
func heightWithConstrainedWidth(width: CGFloat, font: UIFont) -> CGFloat {
let constraintRect = CGSize(width: width, height: CGFloat.max)
let option = NSStringDrawingOptions.UsesFontLeading.union(.UsesLineFragmentOrigin)
let boundingBox = self.boundingRectWithSize(constraintRect, options: option, attributes: [NSFontAttributeName: font], context: nil)
print("ex width \(boundingBox.width)")
print("ex height \(boundingBox.height)")
return boundingBox.height
}
}
我在heightForRowAtIndexPath
let myRandomString = "My baby looks like she's ashamed and wants to apologise for something bad she did."
let labelWidth = UIScreen.mainScreen().bounds.width-16
let labelHeight = myRandomString.heightWithConstrainedWidth(labelWidth,font: UIFont.boldSystemFontOfSize(17))
调用它,我得到:
ex width 359.0
ex height 40.57421875
正如你可以看到我的宽度是正确的(我强迫它),但我的身高是不正确的,我不明白为什么。
感谢和问候, 埃里克